黄河宁蒙河段冲淤演变特点及趋势分析

Analysis of characteristic and trend of scouring and silting evolution in Ningxia and inner-mongolia reach of Yellow River

通过分析黄河宁蒙河段冲淤演变及河槽过洪能力变化,进一步认识宁蒙河段冲淤演变规律,并根据下河沿水文站设计水沙条件,估算宁蒙河段2020年、2030年的冲淤变化趋势。分析表明:近期宁蒙河段输沙能力降低,巴彦高勒、三湖河口、昭君坟断面平滩流量呈减小趋势,河道淤积加重,支流淤堵干流情况加重。根据下河沿设计水沙条件推算头道拐水沙量以及区间引沙量,采用沙量平衡法,考虑区间支流来沙、区间风沙入黄情况,预估下河沿～头道拐冲淤量,2020年水平,宁蒙河段年均淤积0.78亿t;2030年水平,宁蒙河段年均淤积0.80亿t。

The further understanding of the fluvial processes in Ningxia and Inner-mongolia reach of Yellow River is got through analysing the scouring and silting evolution of the channel and its flood conveyance capacity change.According to the designed water-sediment conditions of Xiaheyan hydrological station,the scouring and silting variation trend in 2020 and 2030 was estimated.The analysis indicated that in recent years,sediment transport capacity of the channel was reduced,bankfull discharge of Bayangaole,Sanhuhekou,Zhaojunfen sections had a decreasing trend,river siltation increased and main stream was clogged by tributaries more frequently.Based on the designed water-sediment conditions of Xiaheyan hydrological station,the quantities of water and sediment of Toudaoguai hydrological station and interzone sediment diversion were calculated,and the scouring and silting amount from Xiaheyan to Toudaoguai was estimated by using sediment balance method and considering incoming sediment from tributaries and windblown sand transported into the main stream of Yellow River.The annual average deposition amount of the channel of Ningxia and Inner-mongolia reach will be 78 million tons in 2020 and 80 million tons in 2030.